Academic literature on the topic 'Broadband Electric Spectroscopy'
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Journal articles on the topic "Broadband Electric Spectroscopy"
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Di Noto, Vito, Matteo Piga, Guinevere A. Giffin, and Giuseppe Pace. "Broadband electric spectroscopy of proton conducting SPEEK membranes." Journal of Membrane Science 390-391 (February 2012): 58–67. http://dx.doi.org/10.1016/j.memsci.2011.10.049.
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Hu, Yunsheng, Yihua Bai, Qing Zhang, and Yuanjie Yang. "Electrically controlled molecular fingerprint retrieval with van der Waals metasurface." Applied Physics Letters 121, no. 14 (2022): 141701. http://dx.doi.org/10.1063/5.0111940.
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Polaritons in two-dimensional van der Waals (vdW) materials possess extreme light confinement, which have emerged as a potential platform for next-generation biosensing and infrared spectroscopy. Here, we propose an ultra-thin and electric tunable graphene/hexagonal boron nitride/graphene metasurface for detecting molecular fingerprints over a broad spectrum. The vdW metasurface supports hybrid plasmon–phonon polariton resonance with high-quality factor (Q > 120) and electrically controlled broadband spectra tunability from 6.5 to 7 μm. After coating a thin layer of bio-molecular (e.g., CBP) on top of the metasurface, the molecular absorption signatures can be readout at multiple spectral points and, thus, achieve broadband fingerprint retrieval of bio-molecules. Additionally, our electric tunable metasurface works as an integrated graphene-based field-effect transistor device, without the need of multiple resonance generators such as angle-resolved or pixelated dielectric metasurfaces for broadband spectra scanning, thereby paving the way for highly sensitive, miniaturized, and electrically addressed biosensing and infrared spectroscopy.
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Kowligy, Abijith S., Henry Timmers, Alexander J. Lind, et al. "Infrared electric field sampled frequency comb spectroscopy." Science Advances 5, no. 6 (2019): eaaw8794. http://dx.doi.org/10.1126/sciadv.aaw8794.
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Probing matter with light in the mid-infrared provides unique insight into molecular composition, structure, and function with high sensitivity. However, laser spectroscopy in this spectral region lacks the broadband or tunable light sources and efficient detectors available in the visible or near-infrared. We overcome these challenges with an approach that unites a compact source of phase-stable, single-cycle, mid-infrared pulses with room temperature electric field–resolved detection at video rates. The ultrashort pulses correspond to laser frequency combs that span 3 to 27 μm (370 to 3333 cm−1), and are measured with dynamic range of >106 and spectral resolution as high as 0.003 cm−1. We highlight the brightness and coherence of our apparatus with gas-, liquid-, and solid-phase spectroscopy that extends over spectral bandwidths comparable to thermal or infrared synchrotron sources. This unique combination enables powerful avenues for rapid detection of biological, chemical, and physical properties of matter with molecular specificity.
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Lasalvia, M., M. Ambrico, T. Ligonzo, G. Perna, P. F. Ambrico, and V. Capozzi. "Keratinocyte cellular damage induced by pesticide doses below the cytotoxic level evidenced by electrical impedance and broadband dielectric spectroscopy." Journal of Physics D: Applied Physics 55, no. 12 (2021): 125402. http://dx.doi.org/10.1088/1361-6463/ac4183.
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Abstract The cellular response of a normal human keratinocyte cell line exposed to non-cytotoxic doses of a deltamethrin-based pesticide was investigated by means of two different electrical impedance data spectroscopy approaches: Nyquist plot and broadband dielectric spectroscopy. The measurements have shown that the membrane capacity increases with pesticide concentration and this facilitates the electric current through cell membranes. Furthermore, the impedance of the extracellular matrix also increases with pesticide concentration, thus reducing the electric current outside the cell. Dielectric permittivity changes in the cellular samples at frequencies larger than 100 Hz. Fluorescence (FL) measurements emphasized an increase in neutral membrane lipids as a consequence of the pesticide exposure. Comparison of FL response of pesticide exposed cells with the control ones showed a time increase in the emission intensity, suggesting the existence of a membrane lipid response aimed at repairing the cell damage due to pesticide exposure. Therefore, both spectroscopic techniques have been demonstrated as potential means to investigate the response to cell stress and damage. This opens up new possibilities in the early diagnosis of cellular modifications related to the pesticide exposure of cells.
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Otagiri, Risa, Hideki Kawai, Masanobu Takatsuka, et al. "Interfacial polarization of in vivo rat sciatic nerve with crush injury studied via broadband dielectric spectroscopy." PLOS ONE 16, no. 6 (2021): e0252589. http://dx.doi.org/10.1371/journal.pone.0252589.
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Electrical stimulation is one of the candidates for elongation-driven regeneration of damaged peripheral nerves. Different organs and tissues have an inherent cell structure and size. This leads to variation in the tissue-specific electrical properties of the frequency of interfacial polarization. Although nervous tissues have a membrane potential, the electrical reaction inside these tissues following electrical stimulation from outside remains unexplored. Furthermore, the pathophysiological reaction of an injured nerve is unclear. Here, we investigated the electrical reaction of injured and non-injured rat sciatic nerves via broadband dielectric spectroscopy. Crush injured and non-injured sciatic nerves of six 12-week-old male Lewis rats were used, 6 days after infliction of the injury. Both sides of the nerves (with and without injury) were exposed, and impedance measurements were performed at room temperature (approximately 25°C) at frequencies ranging from 100 mHz to 5.5 MHz and electric potential ranging from 0.100 to 1.00 V. The measured interfacial polarization potentially originated from the polarization by ion transport around nerve membranes at frequencies between 3.2 kHz and 1.6 MHz. The polarization strength of the injured nerves was smaller than that of non-injured nerves. However, the difference in polarization between injured and non-injured nerves might be caused by inflammation and edema. The suitable frequency range of the interfacial polarization can be expected to be critical for electrical stimulation of injured peripheral nerves.
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Li, Shaobo, Shuming Yang, Fei Wang, Qiang Liu, Biyao Cheng, and Yossi Rosenwaks. "Plasmonic interference modulation for broadband nanofocusing." Nanophotonics 10, no. 16 (2021): 4113–23. http://dx.doi.org/10.1515/nanoph-2021-0405.
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Abstract Metallic plasmonic probes have been successfully applied in near-field imaging, nanolithography, and Raman enhanced spectroscopy because of their ability to squeeze light into nanoscale and provide significant electric field enhancement. Most of these probes rely on nanometric alignment of incident beam and resonant structures with limited spectral bandwidth. This paper proposes and experimentally demonstrates an asymmetric fiber tip for broadband interference nanofocusing within its full optical wavelengths (500–800 nm) at the nanotip with 10 nm apex. The asymmetric geometry consisting of two semicircular slits rotates plasmonic polarization and converts the linearly polarized plasmonic mode to the radially polarized plasmonic mode when the linearly polarized beam couples to the optical fiber. The three-dimensional plasmonic modulation induces circumference interference and nanofocus of surface plasmons, which is significantly different from the nanofocusing through plasmon propagation and plasmon evolution. The plasmonic interference modulation provides fundamental insights into the plasmon engineering and has important applications in plasmon nanophotonic technologies.
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Kanapitsas, A., G. C. Psarras, C. Tsonos, et al. "Magneto-Electric Response and Functionality in Barium Ferrite/Barium Titanate/Epoxy Resin Nanocomposites." Journal of Advanced Physics 6, no. 1 (2017): 69–75. http://dx.doi.org/10.1166/jap.2017.1293.
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Hybrid nanocomposites with barium ferrite and barium titanate nanoparticles embedded within an epoxy resin matrix, were prepared and studied, varying the fillers content. The morphology of the fabricated specimens was examined by means of scanning electron microscopy and energy dispersive X-ray spectroscopy. Dielectric and magnetic properties of the nanocomposites were investigated via broadband dielectric spectroscopy and magnetization tests, respectively. Fine dispersions of nanofillers were detected via electron microscopy in all studied cases. Dielectric permittivity increases with diminishing frequency and increasing temperature and filler content. Recorded relaxation processes are attributed to interfacial polarization, between matrix and nanoparticles, glass to rubber transition of the polymer matrix (α-relaxation), and re-arrangement of polar-side groups of the main polymer chain (β-relaxation). Magnetization and magnetic saturation increase with the amount of barium ferrite nanoparticles.
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Cossel, Kevin C., Daniel N. Gresh, Laura C. Sinclair, et al. "Broadband velocity modulation spectroscopy of HfF+: Towards a measurement of the electron electric dipole moment." Chemical Physics Letters 546 (September 2012): 1–11. http://dx.doi.org/10.1016/j.cplett.2012.06.037.
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Anada, Yui Chi. "Study of Motion of Impurity Ions Making Influence on Electrical Properties of Polymer Solids in Low Frequency Range." Advanced Materials Research 740 (August 2013): 630–35. http://dx.doi.org/10.4028/www.scientific.net/amr.740.630.
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The motion of impurity ions affects the electrical properties of polymer solid. The ions move through free spaces which exist in the non-crystalline part between polymer crystallites. The free spaces have inhomogeneous size distribution depending on a property of polymers or crystallization conditions. The homogeneity or inhomogeneity of the size of the free space affects the ionic motion, and consequently it also affects the electrical properties of polymer solids. In order to study the electrical properties of polymer solids in relation with such motion of impurity ions, the conductivity relaxation time was calculated for isotactic poly (propylene) (iPP), low density poly (ethylene) (LDPE) and plasticized poly (vinyl chloride) with dioctyl phthalate (p-PVC) from the electric modulus as a function of frequency which was observed by means of the Broadband Dielectric Spectroscopy (BDS). The value of the conductivity relaxation time reflects the non-crystalline structure of these polymers.
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Prost, E., V. Loriot, E. Constant, et al. "Air-photonics terahertz platform with versatile micro-controller based interface and data acquisition." Review of Scientific Instruments 93, no. 3 (2022): 033004. http://dx.doi.org/10.1063/5.0082593.
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We present a terahertz (THz) platform employing air plasma produced by an ultrashort two-color laser pulse as a broadband THz source and air biased coherent detection (ABCD) of the THz field. In contrast to previous studies, a simple peak detector connected to a micro-controller board acquires the ABCD-signal coming from the avalanche photodiode. Numerical simulations of the whole setup yield temporal and spectral profiles of the terahertz electric field in both source and detection area. The latter ones are in excellent agreement with our measurements, confirming THz electric fields with peak amplitude in the MV/cm range. We further illustrate the capabilities of the platform by performing THz spectroscopy of water vapor and a polystyrene reference sample.
Dissertations / Theses on the topic "Broadband Electric Spectroscopy"
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Sánchez, Terrones Benjamín. "Broadband electrical impedance spectroscopy for dynamic electrical bio-impedance characterization." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/132281.
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The electrical impedance of biological samples is known in the literature as Electrical Bioimpedance (EBI). The Electrical Bioimpedance enables to characterize physiological conditions and events that are interesting for physiological research and medical diagnosis. Although the Electrical Bioimpedance weakness is that it depends on many physiological parameters, on the other hand, it is suitable for many medical applications where minimally invasive and real-time measurements with simple and practical implementations are needed.
The Electrical Impedance Spectroscopy (EIS) techniques based on broadband excitations are expected to help to understand various unsolved problems in biomedical applications. Broadband EIS opens up the possibility to reduce drastically the measuring time for acquiring EBI time-variations but, at the same time, measuring in a short time compromises the EBI accuracy. The way to overcome this intrinsic loss of accuracy relies on the design of the appropriate time/frequency input excitation properties and the use of the suitable spectral analysis processing techniques.
The presented thesis covers the topics related to study of broadband excitations for Impedance Spectroscopy in biomedical applications and, more specific, the influence of the multisine excitation time/frequency properties on the impedance spectrum accuracy and its optimization. Furthermore, an advanced fast signal processing method has been implemented to process in real-time EBI data corrupted by transients, a common situation when measuring in a short measuring time. Despite being the goal to apply all this knowledge for myocardial tissue regeneration monitoring, at the moment of drafting the thesis, any of the research projects that have supported this thesis have issued functional beating tissue. For that reason, the theory presented has been validated by a set of experimental measurements over animals and patients where the impedance spectrum time-varying properties were pretended to be characterized.
The thesis presents novel findings of relevance of a successful application of broadband EIS in two different measurement campaigns where it has been put in practice: (1) within the collaboration of the pneumology and cardiology service from Hospital Santa Creu i Sant Pau for in-vivo human lung tissue characterization, and (2), within the measurement of animal healthy myocardium tissue electrical impedance including its dynamic behavior during the cardiac cycle.
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Piga, Matteo. "New hybrid inorganic-organic proton conducting membranes for PEMFC: synthesis, properties and conduction mechanisms." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3421723.
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Electrochemical devices for the conversion of chemical energy into electrical power, such as proton exchange membrane fuel cells (PEMFCs), are of intense interest to industry and the scientific community because of their high energy conversion efficiency, low environmental impact, and the possibility for use in a wide variety of applications from portable electronic devices to light-duty electric vehicles. At the core of the fuel cell is a PEM that allows the transport of hydrogen ions, evolved at the anode, to the cathode where oxygen is reduced to water. Todays prevalent PEMs feature perfluorinated main chains functionalized with perfluoroether side chains terminated with acidic -SO3H groups. These materials (DupontTM Nafion®, Asashi Aciplex®, Dow®, and Flemion®) generally are characterized by a high chemical, thermal and mechanical stability; they also exhibit good proton conductivity at high levels of hydration. The hydration requirements limit the widespread commercial use of conventional PEMs, which have inadequate proton conductivity at temperatures above 90C and at low values of relative humidity. Fuel cells capable of operating above 120C at low levels of hydration would: obviate the need of bulky and expensive water management modules, simplify thermal management; and reduce the impact of catalyst poisons such as carbon monoxide. In an effort to overcome the limitations of conventional PEMs, this work reports the synthesis and characterization of new proton conducting membrane alternatives to classic fluorinated polymers for application in PEMFCs. The materials were synthesized according to two distinct strategies: 1) dope a Nafion membrane in order to improve its thermo-mechanical properties and proton conductivity or extend its operating conditions to temperatures above 100°C and an anhydrous environment; 2) synthesize and characterize proton exchange membranes based on polybenzimidazole and polysulfone as an alternative to perfluorinated polymers.
The first point regarded the study of two different systems obtained by doping a Nafion membrane with the [(ZrO2)(Ta2O5)0.119] inorganic “core-shell” nanofiller or with two different proton conducting ionic liquids, triethylammonium methanesulfonate and triethylammonium perfluorobutanesulfonate. The study of new PEMs alternative to fluorinated polymers has been developed considering polybenzimidazole and sulfonated poly(p-phenylenesulfone) membranes whose properties have been modulated by the addition of phosphoric acid and an hybrid filler or poly(1-oxotrimethylene) and silica, respectively. All the proposed materials were extensively characterized in terms of their thermal, mechanical, structural and electrical properties in order to highlight the interactions between the different components present within the membranes. These interactions govern the membranes macroscopic properties that need to be improved in order to optimize and predict the behavior of these materials under operating conditions in fuel cells.<br>Celle a combustibile basate su membrane a scambio protonico (PEMFCs) sono dispositivi elettrochimici per la conversione di energia chimica in energia elettrica. Le PEMFCs suscitano notevole interesse sia nel mondo industriale che accademico a causa della loro elevata efficienza di conversione, basso impatto ambientale e vasta gamma di utilizzo che spazia dall’elettronica portatile fino all’autotrazione.
All’interno della cella a combustibile si trova la membrana a scambio protonico (PEM), che consente il trasferimento di protoni dall’anodo al catodo.
Attualmente le membrane polimeriche a scambio protonico maggiormente utilizzate sono costituite da polimeri fluorurati funzionalizzati con gruppi polieterei terminanti con gruppi acidi (tipicamente -SO3H). Questi materiali (DupontTM Nafion®, Asashi Aciplex®, Dow®, and Flemion®) generalmente presentano elevata stabilità chimica, termica e meccanica ma tuttavia mostrano valori di conducibilità sufficienti per il loro impiego in cella a combustibile solo per elevati livelli di idratazione. La scarsa conducibilità protonica dei polimeri perfluorurati per temperature maggiori di 90°C e bassi livelli di idratazione limita fortemente il loro utilizzo su larga scala.
Celle a combustibile che operano a temperature superiori a 120°C e bassi livelli di idratazione non necessitano dell’introduzione di sistemi di umidificazione e raffreddamento, riducendo il costo e semplificando la realizzazione ed ingegnerizzazione del dispositivo finale. Inoltre, l’aumento di temperatura riduce l’avvelenamento del catalizzatore da contaminanti esterni come ad esempio il monossido di carbonio.
Al fine di superare le limitazioni delle PEMs convenzionali, questo lavoro di tesi riporta la sintesi e la caratterizzazione di nuove membrane polimeriche a conducibilità protonica alternative ai classici polimeri fluorurati per applicazioni in celle a combustibile.
I materiali sono stati sintetizzati seguendo due diverse strategie: 1) drogare una membrane di Nafion al fine di aumentare il suo intervallo di stabilità termico e meccanico e la sua conducibilità protonica così da estenderne le condizioni operative di utilizzo a temperature maggiori di 90°C e per bassi o nulli livelli di idratazione; 2) sintetizzare e caratterizzare PEMs basate su polibenzimidazolo e polisulfone come materiali alternativi ai classici polimeri fluorurati.
Il primo punto ha riguardato lo studio di due diversi sistemi ottenuti drogando una membrana di Nafion con il filler inorganico [(ZrO2)(Ta2O5)0.119] oppure con due diversi liquidi ionici a conducibilità protonica, il trietilammonio-metansolfonato ed il trietilammonio-perfluorobutansolfonato.
Lo studio di nuove membrane alternative ai polimeri fluorurati è stato sviluppato considerando membrane di polibenzimidazolo (PBI) e polisulfone solfonato (sPSO2) le cui proprietà sono state modulate dall’aggiunta di acido fosforico e di un filler ibrido a base di silice funzionalizzata (nel caso del PBI) o di poliossotrimetilene e silice (per le membrane a base di sPSO2).
Al fine di delucidare le interazioni esistenti tra i diversi componenti presenti all’interno delle membrane, tutti i materiali sono stati ampiamente caratterizzati dal punto di vista delle loro proprietà termiche, meccaniche, strutturali ed elettriche. Queste interazioni governano le proprietà macroscopiche delle membrane che necessitano di essere migliorate al fine di ottimizzare e prevedere il comportamento di questi materiali in condizioni di esercizio in celle a combustibile.
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Glickstein, Jarred S. "Automated Polarisation Enhanced Broadband Nuclear Quadrupole Resonance Spectroscopy." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1513081362905414.
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Waligo, Alfred. "Condition monitoring of lithium-ion batteries using broadband multisine excitation and electrochemical impedance spectroscopy." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28109.
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Electrochemical Impedance Spectroscopy (EIS) is a well-known technique that has been employed on various electrochemical cells to obtain their impedance spectra. Lithium-ion(Li-ion) cells are some of the cells to which it has been applied. The impedance spectra obtained from EIS can be used to estimate various batteries State of Health (SOH) and State of Charge (SOC) characteristics. The lengthy acquisition time associated with standard EIS makes it unsuitable for rapid on-line impedance measurements. Alternative methods that take a shorter time have therefore been proposed. This study compares the spectra obtained by the Harmonic Compensated Synchronous Detection (HCSD) broadband signal technique with the EIS and a custom Broadband Impedance Spectroscopy (BIS) technique, at different states of charge, which mimic a real-time load. The test cells are industry standard Nickel-Cobalt and Manganese Oxide (NCM) Li-ion cells. The BIS technique is like HCSD in the selection of frequencies; however, the amplitude of the excitation broadband signal is varied to match the impedance magnitude response of the cell. Also, parameter extraction is performed on both EIS and BIS techniques for fault detection purposes.
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Moreno, Mencía David. "The application of broadband ultrafast spectroscopy to reveal structural, magnetic and electronic dynamics in quantum materials." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673233.
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In the last decades, quantum materials have received much attention in the field of condensed matter physics due, in part, to their exotic properties. These are difficult to understand as they result from multiple physical interactions with similar strength, such as charge, spin, orbitals and phonon degrees of freedom.
To study and control these interactions, the use of light has emerged as a powerful tool. For example, thanks to recent advantages on X-ray sources it has been possible to improve our understanding of how the atomic structure of quantum materials changes upon photo-excitation. However, these experiments are difficult and there are only a few facilities in the world to perform them. In contrast to X-ray sources, table-top ultrafast laser systems allow us to measure in a systematic manner by performing optical pump-probe spectroscopy. The versatility of this approach enables the simultaneous monitoring of the different degrees of freedom that dictate the properties of quantum materials. In this thesis, we use pump-probe broadband spectroscopy in the visible region to study the structural, electronic and magnetic dynamics with unprecedented detail in two key quantum materials such as Sr3Ir2O7 and V2O3.
In Sr3Ir2O7, a compound that undergoes a magnetic phase transition, firstly we study how photo-excitation affects to the reflectivity at a wide range of energies. This provides us information about the electronic and structural properties of this compound. Secondly, we show how to control magnetic order by photoexcitation and demonstrate that light can non-thermally suppress the magnetic long-range order in this material.
In V2O3 we characterize its insulator to metal and structural phase transitions. In the metallic state, we show that a key phonon mode is very sensitive to sample inhomogeneity. When taking this into account, we find no evidence for non-thermal lattice dynamics in contrast to existing literature. Furthermore, we show that the light induced transition from the insulator to metallic phase proceeds along a highly damped and incoherent pathway, where vibrational coherence is not observed.<br>En las últimas décadas, los materiales cuánticos han generado un gran interés en el campo de la materia condensada debido, en parte, a sus exóticas propiedades. Éstas son difíciles de comprender ya que surgen de una compleja interacción física entre los distintos grados de libertad como la carga, el espín, el momento orbital y fonones. El uso de la luz surge como una herramienta poderosa para estudiar y controlar estas interacciones. Por ejemplo, gracias a los avances en los sistemas de rayos X se ha mejorado nuestra comprensión de cómo la estructura atómica de los materiales cuánticos cambia bajo la fotoexcitación. Sin embargo, estos experimentos son difíciles y, además, hay escasas instalaciones alrededor del mundo para poder realizarlos. A diferencia de los sistemas de rayos X, los sistemas láseres ultrarrápidos nos permiten medir de una manera sistemática mediante la espectroscopía de bomba-sonda. La versatilidad de esta técnica permite monitorizar de manera simultánea los diferentes grados de libertad que determinan las propiedades de los materiales cuánticos. En esta tesis, utilizamos espectroscopía de bomba-sonda de banda ancha en la región visible para estudiar las dinámicas estructurales, electrónicas y magnéticas con detalles sin precedentes en dos materiales cuánticos clave como Sr3Ir2O7 y V2O3. En Sr3Ir2O7, compuesto que experimenta una transición de fase magnética, estudiamos en primer lugar cómo la fotoexcitación afecta a la reflectividad en un amplio rango de energías. Esto nos proporciona información sobre las propiedades estructurales y electrónicas de dicho compuesto. En segundo lugar, mostramos cómo se puede controlar el orden magnético mediante la fotoexcitación, demostrando que la luz puede suprimir el orden magnético de largo alcance de manera no térmica en este material. En V2O3 caracterizamos las transiciones metal-aislante y estructurales del material. En el estado metálico mostramos que un modo de los fonones clave es muy sensible a la falta de homogeneidad de la muestra. Al tener esto en cuenta, no encontramos pruebas de cambios estructurales no-termodinámicos, en contraste con la literatura existente. Además, mostramos que la transición de fase metal-aislante inducida por la luz se realiza de una manera altamente amortiguada e incoherente, donde no se observa la frecuencia vibratoria.<br>Fotònica
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Arenas, Benjamin Edades [Verfasser]. "High-resolution broadband rotational spectroscopy and electrical discharge experiments of astrochemically relevant molecules / Benjamin Edades Arenas." Hamburg : Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky, 2020. http://d-nb.info/1223095878/34.
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SUN, C. "Electrical energy storage by electrochemical vanadium redox flow battery methods." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3424975.
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Redox flow batteries (RFBs) are electrochemical cells that are able to reversibly convert the chemical energy stored into the redox couples into electrical power. Vanadium redox flow batteries (VRFBs) exploit redox couples both based on vanadium species. To make VRFB technology commercially viable, technical and economic barriers including high capital cost and rapid capacity decay need to be addressed. The primary objective of this thesis is to achieve high performance VRFB with long durability, mainly by reducing the vanadium permeability through the membrane. Nowadays perfluorosulfonic acid membranes are widely used in VRFB, such as Nafion. Nafion has high chemical and mechanical stability, and it exhibits good proton conductivity. Nevertheless, the VRFB cell with Nafion membrane has fast capacity decay due to the high vanadium crossover.
In an effort to overcome the limitations of Nafion, this thesis reports the synthesis and characterization of hybrid inorganic-organic proton-conducting membrane alternatives to classic perfluorinated ionomers. Two families of hybrid membranes were synthesized:
1) Nafion membrane doped with WO3 nanofiller, in order to reduce its vanadium crossover while maintaining the high proton conductivity;
2) synthesis of sulfonated poly (ether ether ketone) (SPEEK) membrane with optimized degree of sulfonation as an alternative low-cost membrane. Then further dope the SPEEK membrane with WO3 to reduce vanadium crossover.
For all the hybrid membranes prepared by a solvent-casting procedure, the introduction of WO3 nanoparticles does not alter significantly the thermal degradation events of the polymer host and the hybrid membranes maintain the good thermal stability. MDSC reveals that in hybrid membranes the endothermic events are slightly shifted attributed to the formation of “dynamic crosslinks” between the WO3 nanoparticles and the polymer host, that stabilize the hybrid membrane. The hydrophilic domains of the polymer host are reduced in size as the content of WO3 is raised. The water uptake of hybrid membranes decreases with the increasing loading of WO3 nanofillers; as a consequence, the pathways of charge migration become more tortuous. While the higher charge migration tortuosity would correspond to a dramatically lower permeability to vanadium species. The tortuosity for protons is likely much less than that for vanadium, as the vanadium ions are only passing through the bulk water, while the protons are also delocalized at the polymer-nanofiller interfaces in the presence of interface water. The vanadium permeability of hybrid membranes decreases significantly and the ion selectivity is much improved in comparison with Nafion. The hybrid membranes with highest ion selectivity are chosen for VRFB single cell test. They exhibits a higher coulombic efficiency in comparison with the Nafion 212 reference. The reduced permeation of vanadium species is also revealed by the lower discharge capacity decay and longer self-discharge times for the hybrid membranes. Therefore, the new family of hybrid membranes may be promising candidates for application in VRFBs.
The final chapter describes the study by Raman spectroscopy of the species present in the positive feed of a VRFB as a function of the state of charge (SOC). Changes in complexation due to presence of stable oxygenated coordination complexes of vanadium, also interacting strongly with HSO4- and SO42- ligands, are put in evidence. In particular, it is demonstrated that the positive feed includes additional species beyond VO2+ and VO2+, with a particular reference to dimers such as HV2O5- and H3V2O7-. Such species may be accounted to understand in detail the charge-discharge processes taking place at the electrodes of a VRFB. Indeed, on these bases, the processes are expected to involve a broad distribution of V(IV) and V(V) species, that may end up affecting significantly crucial macroscopic features of the overall VRFB.<br>Le batterie Redox a Flusso (RFB) sono celle elettrochimiche capaci di convertire reversibilmente l'energia chimica immagazzinata in coppie redox in energia elettrica. Le batterie a flusso al vanadio (VRFB) sfruttano coppie redox entrambe basate su specie di vanadio. Per far sì che la tecnologia VRFB sia commercialmente valida, occorre superare barriere tecniche ed economiche che includono elevati costi di capitale ed un rapido decadimento della capacità. L'obiettivo principale di questa tesi è di ottenere VRFB ad alte prestazioni e di lunga durata, principalmente riducendo la permeabilità del vanadio attraverso la membrana. Al giorno d'oggi nelle VRFB vengono utilizzate membrane a base di acido perfluorosolfonico, come il Nafion. Il Nafion ha un'elevata stabilità chimica e meccanica, e presenta una buona conducibilità protonica. La VRFB con membrana al Nafion hanno un rapido decadimento della capacità a causa dell'alto crossover del vanadio.
Per superare i limiti del Nafion, questa tesi riporta la sintesi e la caratterizzazione di membrane ibride inorganico-organiche conduttrici di protoni alternative agli ionomeri perfluorurati. Due famiglie di membrane ibride sono state ottenute:
1) membrana di Nafion drogata con nanofiller WO3, per ridurre il crossover del vanadio mantenendo un’elevata conducibilità protonica;
2) sintesi di una membrana a base di poli(etere-etere-chetone) solfonato (SPEEK), con grado di solfonazione ottimizzato. Anche la membrana a base di SPEEK viene poi drogata con WO3 per ridurre il crossover del vanadio.
Nelle membrane ibride preparate mediante una procedura di solvent-casting, l'introduzione di nanoparticelle di WO3 non altera in modo significativo gli eventi di degradazione termica della matrice polimerica, mantenendo così una buona stabilità termica. Misure MDSC rivelano che nelle membrane ibride gli eventi termici sono leggermente spostati a causa della formazione di "crosslink dinamici" tra le nanoparticelle di WO3 e la matrice polimerica, che stabilizzano la membrana. La dimensione dei domini idrofili e l’assorbimento d’acqua della mambrana si riducono all’aumentare del contenuto di WO3. Di conseguenza, i percorsi di migrazione di carica diventano più tortuosi. Questa maggiore tortuosità alla migrazione di carica corrisponde ad una permeabilità inferiore delle specie vanadio. Al contrario del vanadio, la tortuosità ha probabilmente un effetto inferiore per i protoni, poiché gli ioni di vanadio attraversano solo i domini massivi di acqua, mentre i protoni vengono scambiati anche alle interfacce polimero-nanofiller. Così, la permeabilità al vanadio delle membrane ibride diminuisce significativamente e la selettività degli ioni è molto migliorata rispetto al Nafion. Le migliori membrane ibride sono scelte per il test in cella VRFB. Esse esibiscono una maggiore efficienza coulombica rispetto al riferimento Nafion 212. La ridotta permeazione delle specie di vanadio è rivelata anche dal minore decadimento della capacità di scarica e dai tempi di autoscarica più lunghi per le membrane ibride. Pertanto, la nuova famiglia di membrane ibride è un promettente candidato per l'applicazione in VRFB.
Il capitolo finale descrive lo studio, attraverso la spettroscopia Raman, delle specie presenti nella soluzione positiva (catolita) di una VRFB in funzione dello stato di carica (SOC). Gli equilibri dovuti alla presenza di complessi di coordinazione del vanadio, che interagiscono fortemente con i leganti HSO4- e SO42-, vengono evidenziati. In particolare, viene dimostrato come il catolita includa specie addizionali oltre a VO2+ e VO2+, quali HV2O5- e H3V2O7-. La presenza di tali specie deve essere considerata per comprendere in dettaglio i processi di scarica e carica che avvengono agli elettrodi di una VRFB. Infatti, su queste basi, ci si aspetta il coinvolgimento di un'ampia distribuzione di specie V(IV) e V(V), che potrebbero influenzare le caratteristiche macroscopiche significativamente cruciali di una VRFB.
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Tseng, Jung-Kai. "Enhanced Dielectric Properties of Multilayer Capacitor Film via Interfacial Polarization." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1449137228.
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Pirondelli, Andrea. "Production and Electrical Characterization of Low Density Polyethylene-based Micro- and Nano-dielectrics containing Graphene Oxide, Functionalized Graphene and Carbon Black additives." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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Oggigiorno la ricerca di nuovi materiali per gradatori di campo da impiegarsi in accessori di cavi ha iniziato a studiare alcuni materiali nano dielettrici con proprietà elettriche non lineari con la tensione ed aventi proprietà migliorate rispetto al materiale base. Per questo motivo in questo elaborato si sono studiati materiali nanostrutturati a base di polietilene a bassa densità (LDPE) contenenti nano polveri di grafene funzionalizzato (G*), ossido di grafene (GO) e carbon black (CB). Il primo obiettivo è stato quello di selezionare e ottimizzare i metodi di fabbricazione dei provini. La procedura di produzione è suddivisa in due parti. Nella prima parte è stata utilizzatala tecnica del ball-milling, mentre nella seconda un pressa termica (thermal pressing). Mediante la spettroscopia dielettrica a banda larga (BDS) si sono misurate le componenti reali e immaginarie della permettività e il modulo della conducibilità del materiale, in tensione alternata. Il miglioramento delle proprietà rispetto al provino di base composto dal solo polietilene si sono ottenute quando il quantitativo delle nanopolveri era maggiore. Le misure sono state effettuate sia a 3 V che a 1 kV. Attraverso misurazioni di termogravimetria (TGA) si è osservato l’aumento della resistenza termica di tutti i provini, soprattutto nel caso quando la % di nanopolveri è maggiore. Per i provini LDPE + 0.3 wt% GO e LDPE + 0.3 wt% G* si è misurata la resistenza alle scariche parziali attraverso la valutazione dell’erosione superficiale dei provini. Per il provino contenente G* è stato registrato una diminuzione del 22% del volume eroso, rispetto al materiale base, mentre per quello contenente GO non vi sono state variazioni significative. Infine si è ricercata la resistenza al breakdown di questi ultimi tre provini sopra citati. Per la caratterizzazione si è fatto uso della distribuzione di Weibull. Lo scale parameter α risulta aumentare solo per il provino LDPE + 0.3 wt% G*.
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Relaix, Sabrina. "Cristaux liquides cholestériques en conditions non usuelles de photogélification : modulation du profil de réflexion de la lumière." Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00179999.
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De part sa structuration en hélice, un Cristal Liquide Cholestérique (CLC) possède des propriétés optiques singulières. La lumière incidente sur un CLC est réfléchie sélectivement, avec une longueur d'onde λ0 associée proportionnelle au pas hélicoïdal et ceci sur une largeur spectrale de quelques dizaines de nm autour de λ0. La quantité de lumière réfléchie est par ailleurs limitée à 50% de la lumière ambiante (non polarisée). <br /><br />Les travaux de thèse se sont focalisés sur l'obtention de propriétés de réflexion de cholestériques gélifiés atypiques, avec deux objectifs de recherche: l'élargissement de la bande de réflexion et l'accroissement de la quantité de lumière réfléchie. <br /><br />La première partie du manuscrit de thèse propose un procédé d'élaboration permettant un élargissement de la bande de réflexion de gels de CLC. Cet objectif est atteint par l'utilisation d'un CLC absorbant la lumière UV, à l'origine d'un gradient d'intensité lors de la gélification. Des études par microscopie optique, spectrophotométrie et microscopie électronique en transmission ont permis de déterminer la distribution structurale à l'origine de la distribution des longueurs d'onde de réflexion observée.<br /><br />La seconde partie du manuscrit se focalise sur l'augmentation de la quantité de lumière réfléchie par un gel réalisé à partir d'un mélange cholestérique qui voit son sens d'hélicité changer avec la température. L'impact de l'histoire de la polymérisation et du parcours en température après gélification sur les propriétés du profil de réflexion sera analysé avec une attention particulière sur la nature et la quantité de la polarisation du faisceau réfléchi.
Books on the topic "Broadband Electric Spectroscopy"
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1953-, Runt James P., and Fitzgerald John J, eds. Dielectric spectroscopy of polymeric materials: Fundamentals and applications. American Chemical Society, 1997.
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Usmanov, S. M. Numerical methods of solving ill-posed problems of dielectric spectrometry. Nova Science Publishers, 2002.
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Usmanov, S. M. Numerical methods of solving ill-posed problems of dielectric spectrometry. Nova Science, 2003.
Find full textBook chapters on the topic "Broadband Electric Spectroscopy"
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Adrjanowicz, Karolina, and Ranko Richert. "Control of Crystallization Pathways by Electric Fields." In Crystallization as Studied by Broadband Dielectric Spectroscopy. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-56186-4_6.
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Prokhorenko, Valentyn I., Alessandra Picchiotti, Samansa Maneshi, and R. J. Dwayne Miller. "Broadband Electronic Two-Dimensional Spectroscopy in the Deep UV." In Springer Proceedings in Physics. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13242-6_105.
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Serghei, Anatoli, Joshua R. Sangoro, and Friedrich Kremer. "Broadband Dielectric Spectroscopy on Electrode Polarization and Its Scaling." In Electrical Phenomena at Interfaces and Biointerfaces. John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118135440.ch15.
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Schlau-Cohen, Gabriela S., Tessa R. Calhoun, Gregory S. Engel, et al. "Mapping Parallel Pathways of Energy Flow in LHCII with Broadband 2D Electronic Spectroscopy." In Springer Series in Chemical Physics. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-95946-5_194.
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Lüer, L., J. Crochet, T. Hertel, D. Polli, and G. Lanzani. "Evidence for electron correlation in (6,5) carbon nanotubes from pump-probe spectroscopy with broadband pulses." In Springer Series in Chemical Physics. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-95946-5_85.
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Poplavko, Yuriy. "Broadband dielectric spectroscopy." In Dielectric Spectroscopy of Electronic Materials. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-823518-8.00001-3.
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Cina, Jeffrey A. "Transient-absorption spectroscopy: Making ultrashort pulses worthwhile." In Getting Started on Time-Resolved Molecular Spectroscopy. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780199590315.003.0003.
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This chapter explains measurements in which the effects of prior electronic and vibrational excitation by a vibrationally brief, electronically resonant pump pulse on the spectrally resolved transmission of a variably delayed broadband probe pulse are monitored. Illustrative transient-absorption signal calculations for model systems are presented and interpreted in terms of semi-classically described quantum mechanical overlaps between contributing multi-pulse nuclear wave packets.
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Parambil Safna Hussan, Kodakkat, Indulekha Jayarajan Jithin Raj, Sailaja Urpayil, and Mohamed Shahin Thayyil. "Studies on Histamine H2-Receptor Antagonists by Using Density Functional Theory." In Drug Design - Novel Advances in the Omics Field and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95322.
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Density functional theory (DFT) is a quantum mechanical approach used to investigate the electronic structure (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases. In this work, we have used DFT/B3LYP/6-31+G(d) level of theory to get insight into the molecular geometry and thermochemical properties of histamine H2-receptor antagonists. Histamine H2-receptor antagonists or H2 blockers are a group of pharmaceutical ingredients that reduce the amount of acid produced by the cells in the lining of the stomach. The potential H2 blockers include cimetidine, famotidine, nizatidine, and ranitidine. The detailed theoretical investigation on the listed H2 blockers in terms of their thermochemical parameters and global descriptive parameters revealed that, though famotidine is the best among them with highest Gibbs free energy, nizatidine showed higher biological activity with high softness, low hardness, and high electrophilicity index. The theoretical vibrational spectra of these four Histamine H2-receptor antagonists were analyzed and the infrared spectra of nizatidine was compared with the experimental IR spectra, and found to be good agreement with the experimental values. Further, frontier molecular orbitals especially the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were determined and the activation energy of the selected samples were calculated. In addition to this, the amorphisation technique were employed to enhance the solubility and bio availability of the best biologically active H2 blocker nizatidine using broadband dielectric spectroscopy.
Conference papers on the topic "Broadband Electric Spectroscopy"
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Binjrajka, V., C. C. Chang, A. W. R. Emanuel, D. E. Leaird, and A. M. Weiner. "“Pulse Shaping” of Incoherent Light by Use of a Liquid Crystal Modulator Array." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fe.8.
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We apply femtosecond pulse shaping techniques[1,2] for electronically programmable phase filtering of broadband incoherent light at 1.5 µ m. Pulse shaping applied to incoherent light results in tailoring of the electric field coherence function, in contrast to the pulse intensity and phase profile, as in the usual coherent femtosecond pulse shaping experiments. Our results may have applications in broadband communications using coherence coding for time-division multiplexed data transmission[3] or code-division networking[4] as well as in time-resolved spectroscopy using incoherent light.
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Jaldurgam, Farheen Fathima, Zubair Ahmad, and Farid Touati. "Optimum Sintering Method and temperature for Cold Compact Bismuth Telluride pellets for Thermoelectric applications." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0053.
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This work intends to investigate the optimum sintering method and temperature that can improve the efficiency of bismuth telluride cold compact pellets for thermoelectric applications. Different p-type and n-type bismuth telluride cold compact pellets were treated using three different sintering techniques and conditions: pressure less (conventional), microwave, and tube (using argon environment) at temperatures 250°C, 300°C, 350°C, and 400°C. The structural, microscopic, electron transport, thermal, and dielectric properties of the pristine and sintered samples were examined. Broadband dielectric spectroscopy was performed to extract a detailed picture of the dielectric properties of the samples. Even though each type of sintering had its own merits and demerits, the optimum conditions for enhanced electric and thermal features were found in microwave furnaces followed by tube and conventional. Low thermal conductivity of 0.4 W/m/K was observed in the samples sintered at 250 °C while the increase in sintering temperature from 250°C to 300°C improved the crystallinity of the material. Moreover, the crystal structure of the bismuth telluride altered with the occurrence of higher oxidation leading to the formation of high bismuth telluride oxide phases at sintering temperatures above 300°C, more dominantly in the n-type samples.
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Baxter, G. W., J. G. Haub, and B. J. Orr. "Multiplex coherent anti-Stokes Raman spectroscopy using a pulsed optical parametric oscillator: comparison of broadband and two-colour techniques." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1996. http://dx.doi.org/10.1364/cleo_europe.1996.cwc3.
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Coherent anti-Stokes Raman spectroscopy (CARS) is a form of nonlinear-optical spectroscopy that is useful for spectroscopic sensing of high-temperature media. Earlier research1 evaluated optical parametric oscillator (OPO) devices as an alternative to dye lasers in providing tunable coherent light for this purpose. Further development of the OPO CARS theme follows demonstrations2,3 of how to control the optical bandwidth and output wavelengths of a pulsed OPO with a passive ring cavity, injection-seeded by a single-mode external-cavity diode laser (ECDL). We have succeeded in injection seeding a single pulsed OPO at two separate optical frequencies that fall within its intrinsically broad optical bandwidth, using a pair of ECDLs. This OPO-based strategy enables single-shot, two-colour multiplex CARS measurements4 that can be used for combustion diagnostics, as has previously been demonstrated with dye-laser sources.5
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Mathies, Richard A. "Femtosecond broadband Stimulated Raman Spectroscopy." In 2008 Conference on Lasers and Electro-Optics (CLEO). IEEE, 2008. http://dx.doi.org/10.1109/cleo.2008.4552405.
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Nguyen, Hoang H., Yin Song, Elizabeth L. Maret, Yogita Silori, and Jennifer P. Ogilvie. "Multispectral Two-Dimensional Electronic Spectroscopy of the Photosystem II Reaction Center." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.m1a.2.
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We present two-dimensional electronic spectroscopy of the photosystem II reaction center at 77K, exciting the spectrally-congested Qy region and probing multiple spectral regions spanning the visible to the mid-IR to extract broadband charge separation signatures.
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Schins, J. M., P. Breger, P. Agostini, et al. "Observation of laser-assisted Auger decay in argon." In High Resolution Fourier Transform Spectroscopy. Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.wd1.
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We investigated the effect of an intense dressing field on the energies of electrons ejected in an Auger process by means of electron spectroscopy. An amplified Ti:S laser provides infrared (800 nm) pulses of 40 mJ ranging from 150 femtoseconds to 8 picoseconds.[1] Part of the infrared beam is focused onto a liquid metal (gallium) target to produce broadband X-radiation. Auger electrons resulting from the X-induced LMM transition in argon[2] are detected in a time-of-flight electron spectrometer. When the X-ray beam and the infrared dressing beam overlap in space and time, sidebands appear around the Auger peaks, corresponding to absorption or emission of photons from the dressing field.
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Tenne, Ron, Peter Fischer, Gabriel Fitzky, Davide Bossini, and Alfred Leitenstorfer. "Terahertz Shockwave Spectroscopy: Probing Free Electrons in a Narrow-Band Semiconductor." In CLEO: QELS_Fundamental Science. Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_qels.2022.fm4n.2.
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Separating the contribution of free and bound charge carriers is a fundamental challenge in pump-probe spectroscopy. We present a novel optical-pump broadband-terahertz-probe technique that addresses free electrons specifically by capturing the full electron plasma feature.
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Sechrist, Riley, Rhiannon Willow, Yogita Silori, Arkaprabha Konar, and Jennifer P. Ogilvie. "Multiexcitation Global Analysis of Two-dimensional Electronic Spectroscopy of the Bacterial Reaction Center." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.m4a.5.
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We report two-dimensional electronic spectroscopy (2DES) experiments on the bacterial reaction center from purple bacteria mutant W(M250)V, exciting the Qy region and probing multiple spectral regions spanning the visible–mid-IR to extract broadband signatures of charge separation.
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Kachanov, A., F. Stoeckel, J. Yu, E. Frejafon, and J. P. Wolf. "All solid-state compact intracavity spectrometer based on a diode pumped LISAF laser." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1996. http://dx.doi.org/10.1364/cleo_europe.1996.cwd4.
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Intracavity laser absorption spectroscopy (ICLAS) is an extremely sensitive method of measurement of very weak absorption spectra. ICLAS is based on very high sensitivity of a broadband laser to narrow absorption lines of the gas tilling the cavity, while the broadband cavity losses are compensated by the gain. This allows to obtain an equivalent absorption path as large as 30000 km and thus to detect absorption lines as weak as 10−11 cm−1. The spectral range of ICLAS is determined by the avalability of broadband homogeneously broadened laser media. Dye, color center and vibronic crystal lasers have been used for ICLAS in the range from 0.4 to 1.5 microns1.
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Merola, Simona S., Bianca M. Vaglieco, and Ezio Mancaruso. "Analysis of Combustion Process in a Transparent Common Rail Diesel Engine by 2D Digital Imaging and Flame Emission Spectroscopy." In ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0644.
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Spectroscopic measurements and 2D digital imaging were used in single cylinder, four-stroke DI diesel engine, optically accessible. It was equipped with a four-valve head and fully flexible electronic controlled ‘Common Rail’ injection system. Three fuel injection strategies, descriptive of the CR diesel engine, were considered. They consisted of a main, a pilot and main and finally pilot, main and post injections. Fuel spray and visible flame propagation were evaluated by digital imaging at high temporal resolution. Autoignition and combustion processes were analysed by broadband ultraviolet-visible flame emission spectroscopy. Radical species such as OH and C2 allowed to characterise the ignition process and pollutant formation. Soot temperature and mass concentration were evaluated by two-colour pyrometry. The presence of C2 and OH radicals strongly characterised CR diesel combustion process during soot formation and evolution. In particular, the high presence of OH concentration for the whole process, from the autoignition to the soot formation and successive phases, contributed to lower the soot levels.